"We are nearing the final stages of our global regulatory approval process," Microsoft general counsel Brad Smith wrote in an update to Microsoft's central corporate blog. "To date we have received approvals from regulatory authorities in 15 markets on five continents. Currently, we are awaiting approval confirmation in the final markets. This work has been progressing, and we expect to close next month, in April 2014."

Smith didn't specify which regulatory authorities are holding out on the approval, but China is chief among them. In response to worries from Samsung and Google, the country has agreed to more closely analyze the deal, and perhaps ask for concessions or at least promises on Windows Phone licensing costs. China is the biggest smartphone market in the world, so getting approval there is clearly a priority for both Microsoft and Nokia.

India is also proving problematic: That country hit Nokia with a $414 million tax bill and a $571 million guarantee that must be paid before the firm can transfer ownership of a factory in that country to Microsoft.

"The completion of this acquisition will mark the first step to bringing Microsoft and the Nokia Devices and Services business together," Mr. Smith noted. "Our acquisition will accelerate our mobile-first, cloud-first imperatives. We're looking forward to accelerating innovation and market adoption for Windows Phones and introducing the next billion customers to Microsoft services via Nokia mobile phones."